Methods for Image Enhancement

1. A method of enhancing an image of a scene, the method comprising the steps of: (a) dividing the image into a plurality of frequency zones; (b) performing a plurality of Richardson and Lucy (RL) iterations of each of the frequency zones to obtain a succession of intermediary enhanced images, wherein a first intermediary enhanced image is obtained prior to a second intermediary enhanced image; (c) transforming each intermediary enhanced image into a frequency space to obtain a respective Fast Fourier Transform (FFT) corresponding to each intermediary enhanced image, and (d) setting a respective FFT of the second intermediary enhanced image to include a respective FFT of the first intermediary enhanced image.

2. The method of claim 1 in which step (b) includes obtaining a third intermediary enhanced image, wherein the third intermediary enhanced image is obtained after the second intermediary enhanced image, step (c) includes setting a respective FFT of the third intermediary enhanced image to include a respective FFT of the first and second intermediary enhanced images to form a composite FFT, and step (d) includes transforming the composite FFT to obtain the enhanced image of the scene.

3. The method of claim 1 in which step (a) includes dividing the image into three frequency zones.

4. The method of claim 3 in which the three frequency zones are determined using a Taguchi orthogonal array computation that minimizes a radiometric error in the enhanced image.

5. The method of claim 1 in which the image is a Rayleigh sampled image obtained by a Rayleigh sampling system.

6. The method of claim 1 in which step (b) includes (i) performing a first number of RL iterations on the image to obtain a first enhanced image including a first frequency zone; (ii) performing a second number of RL iterations on the first enhanced image to obtain a second enhanced image including a second frequency zone; and (iii) performing a third number of RL iterations on the second image to obtain a third enhanced image including a third frequency zone.

7. The method of claim 6 in which the first, second and third number of RL iterations are determined using a Taguchi orthogonal array computation that minimizes a radiometric error in the image.

8. A method of enhancing an image of a scene comprising the steps of: (a) performing a first number of iterations on the image to obtain a first enhanced image; (b) transforming the first enhanced image using a Fast Fourier Transform (FFT); and (c) selecting a portion of a total energy content of the first enhanced image in the FFT below a first frequency; whereby the first frequency and the first number of iterations have values determined by minimizing radiometric errors in the first enhanced image.

9. The method of claim 8 further including the step of: determining a value of the first number of iterations by performing the following: (i) selecting at least two objects within the image, and (ii) minimizing radiometric errors of the selected objects in the first enhanced image.

10. The method of claim 9 in which the radiometric errors of the selected objects are minimized by using a Taguchi orthogonal array.

11. The method of claim 9 in which selecting the objects includes selecting objects of different pixel sizes.

12. The method of claim 8 in which step (a) includes executing a Lucy and Richardson (RL) algorithm to obtain the first enhanced image.

13. The method of claim 8 further including the steps of: (d) performing a second number of iterations on the first enhanced image to obtain a second enhanced image; (e) transforming the second enhanced image using a Fast Fourier Transform (FFT); and (f) selecting a portion of a total energy content of the second enhanced image in the FFT.

14. The method of claim 13 further including the steps of: (g) combining the portions of energy content of the first and second enhanced images in the FFT; and (h) transforming the combined portions of energy content in the FFT into a final enhanced image of the scene.

15. A machine-readable storage medium containing a set of instructions for causing a computer to perform the following steps: (a) executing a Lucy and Richardson (RL) algorithm to enhance an image; and (b) iterating the RL algorithm for a number of iterations, in which the number of iterations is determined by a Taguchi orthogonal array process.

16. The storage medium of claim 15 in which the program further includes the steps of: (c) transforming the enhanced image using a Fast Fourier Transform(FFT); (d) selecting a portion of a total energy content of the enhanced image in the FFT; and (e) inverse transforming the selected portion in the FFT into a final enhanced image.

17. The storage medium of claim 15 in which step (b) includes selecting at least two objects in the image, and determining the number of iterations by minimizing radiometric errors of the selected objects.

18. The storage medium of claim 17 in which minimizing the radiometric errors includes controlling parameters in the RL algorithm, whereby one of the parameters is the number of iterations.

19. A method of enhancing an image of a scene using Richardson and Lucy (RL) iterations, the method comprising the steps of: (a) dividing the image into a plurality of frequency zones, in which the frequency zones are divided by predetermined frequency values; and (b) performing a plurality of RL iterations of each of the frequency zones to obtain an enhanced image of the scene, in which each of the plurality of RL iterations includes a predetermined iteration value; wherein the predetermined frequency values and each of predetermined iteration values are determined using a Taguchi orthogonal array process and selecting objects within the scene and minimizing radiometric errors of the selected objects.

21. The method of claim 20 wherein R of the selected object is approximately 0.60 and the selected object is approximately one pixel in size.

22. The method of claim 20 wherein R of the selected object is approximately 0.10 and the selected object is approximately 5×5 pixels in size.

23. The method of claim 20 wherein R of the selected object is approximately 0.06 and the selected object is approximately 10×10 pixels in size.